Spy pixels or
tracker pixels are
hyperlinks to remote image files in
HTML email messages that have the effect of spying on the person reading the email if the image is downloaded. They are commonly embedded in the HTML of an email as small, imperceptible, transparent graphic files. Spy pixels are commonly used in marketing, and there are several countermeasures in place that aim to block email tracking pixels. However, there are few regulations in place that effectively guard against
email tracking approaches.
History Networked email was pioneered in 1971 by
Ray Tomlinson and has made it much more convenient to send and receive messages as opposed to traditional postal mail. In 2020, there were 4 billion email users worldwide and approximately 306 billion emails sent and received daily. The email sender, however, still has to wait for a reply email from the recipient in order to confirm that their message was delivered. There are some situations where the recipient doesn't respond to the sender even when they have read the email, which is why the email tracking method emerged. Most email services do not provide indicators as to whether an email was read, so third-party applications and plug-ins have provided the convenience of email tracking. The most common method is the email tracking beacon or spy pixel. The tracking process begins when a sender inserts an image tag, represented as , into an HTML-based email. The image tag is linked to a tracking object stored on the server of the sender through a reference
Uniform Resource Locator (URL). Once the mail client is opened, the recipient receives the email through a process whereby the
mail user agent (MUA) synchronizes updates from the recipient's
message transfer agent (MTA) with the local mail repository. When the recipient opens the email, the mail client requests the file that is referenced by the image tag. As a result, the
web server where the file is stored logs the request and returns the image to the recipient. In order to track individual behavior, the tracking object or reference URL has to contain a tag that is unique to each email recipient. Oftentimes, the hash of the recipient's email is used. In contrast, IP address and device information collected from non-tracking images does not reveal specific users' email addresses. When a single email is sent to multiple recipients, the tracking report will normally show the number of emails that have been opened but not the specific recipients who have done so. Although this may be more challenging with web tracking, more advanced web trackers have data collection features, like the
Meta Pixel's advanced matching feature, that allows people to be identified by submitting an email address or other PII on a form page.
Usage Personal use Individuals and business owners may want to use email tracking for a variety of reasons, such as lead generation, event invitations, promotions, newsletters, one-click polls, and teacher-parent communications. They can use services like Yet Another Mail Merge (YAMM), a Google Sheets add-on, to create and send personalized
mail merge campaigns from
Gmail. The sender has the option to enable the tracker and see email open rates, clicks, replies, and bounces. According to YAMM's website: "YAMM embeds a tiny, invisible tracking image (a single-pixel gif, sometimes called a web beacon) within the content of each message. When the recipient opens the message, the tracking image is scanned, referenced and recorded in our system."
Marketing Tracking the behavior of users through mediums like email newsletters and other forms of marketing communication is a competitive advantage in
online marketing. In fact, it is so valuable that there are companies that sell online user data or offer email tracking as a service, such as Bananatag, Mailtrack.io, and Yet Another Mail Merge. Using data to map out the competitive landscape can also help companies derive a competitive strategy and gain a competitive advantage. However, adverse effects from behavioral marketing can include discrimination, including
price discrimination.
Malicious emails Some emails contain malicious content or attachments, and email tracking is used to detect how fast these viruses or malicious programs can spread.
Spying effect The spying effect is that, without the email recipient choosing to do so, the result of the automatic download is to report to the sender of the email: if and when an email is read, when (and how many times) it is read, the
IP address and other identity details of the computer or smartphone used to read the email, and from the latter, the
geographical location of the recipient. This information provides insights into users' email reading behaviors, office and travel times, as well as details about their environment. For example, a board member of a major technology company was caught forwarding confidential information when an email log entry, IP address, and location information were examined simultaneously. Additionally, if spammers send emails to random email addresses, they can identify active accounts in this manner. Furthermore, third-party trackers can be considered as “adversaries” to Internet users because the use of
HTTP cookies,
Flash cookies, and
DOM storage breaks data confidentiality between the users and the websites they interact with. Overall, researchers at
Carnegie Mellon University and
Qualcomm found that many users don't see tracking as black and white. Many want control over tracking and think that it has its benefits, but don't know how to control tracking or distrust current tools. Out of 35 participants in the study, fourteen saw tracking as conditionally positive, eight saw it as generally neutral, nine saw it as generally negative, and the remaining four had mixed feelings. Twelve participants felt resigned to tracking.
Countermeasures Countermeasures include using a plain text
email client, disabling automatic download of images, or, if reading email using a browser, installing an
add-on or
browser extension. The process of email-tracking does not require cookies, which makes it difficult to block without affecting user experience. For example, disabling automatic download of images is easy to implement; however, the trade-off is that it often results in a loss of information, incorrect formatting, a decline in user experience, and incomprehension or confusion. Recent research has focused on using machine learning to develop anti-tracking software for end-users. Privacy tools can have usability flaws which makes it difficult for users to make informed and meaningful decisions. For example, participants in a study thought that they had installed configured a tool successfully when they had not. Additionally, the rise of
ad-blockers and similar privacy tools have led to the emergence of anti ad-blockers, which seek out ad-blockers and try to disable them with various methods, in an escalating ad-blocker arms race. == Notes ==